1. Field of the Invention
The present invention relates to techniques for determining mask patterns for lithographic processes that use photo-masks and write patterns for semiconductor-manufacturing processes that use write devices.
2. Related Art
Lithography processing represents an essential technology for manufacturing Integrated Circuits (IC) and Micro Electro-Mechanical Systems (MEMS). Lithographic techniques are used to define patterns, geometries, features or shapes (henceforth referred to as ‘patterns’) onto an integrated circuit die or semiconductor wafer or chips where the patterns are typically defined by a set of contours, lines, boundaries, edges, or curves (henceforth referred to as ‘contours’), which generally surround, enclose, and/or define the boundary of the various regions which constitute a pattern.
Demand for increased density of features on dies and wafers has resulted in the design of circuits with decreasing minimum dimensions. However, due to the wave nature of light, as dimensions approach sizes comparable to the wavelength of the light used in the photolithography process, the resulting wafer patterns deviate from the corresponding photo-mask patterns and are accompanied by unwanted distortions and artifacts.
Techniques such as Optical Proximity Correction (OPC) attempt to improve resolution and/or a process window in a photolithography process by appropriately pre-distorting the photo-mask pattern such that the wafer pattern is printed more accurately. In addition, other techniques known as resolution enhancement technologies (RET) also modify the design of the photo-mask in order to improve photolithography. However, even with these various approaches, as the density of features has increased, it has become increasingly difficult to determine suitable mask patterns that correspond to photo-mask patterns which print acceptable wafer patterns. In addition, similar challenges occur in mask-less semiconductor processes, such as those that use a write device to print a wafer pattern based on a write pattern
Hence what is needed are improved systems and methods to facilitate determination of mask patterns and/or write patterns.